strace(1M)        UNIX System V(Networking Support Utilities)        strace(1M)


NAME
      strace - print STREAMS trace messages

SYNOPSIS
      strace [ mid sid level ] . . .

DESCRIPTION
      strace without arguments writes all STREAMS event trace messages from all
      drivers and modules to its standard output.  These messages are obtained
      from the STREAMS log driver [log(7)].  If arguments are provided they
      must be in triplets of the form mid, sid, level, where mid is a STREAMS
      module ID number, sid is a sub-ID number, and level is a tracing priority
      level.  Each triplet indicates that tracing messages are to be received
      from the given module/driver, sub-ID (usually indicating minor device),
      and priority level equal to or less than the given level.  The token all
      may be used for any member to indicate no restriction for that attribute.

      The format of each trace message output is:

      <seq> <time> <ticks> <level> <flags> <mid> <sid> <text>

           <seq>     trace sequence number

           <time>    time of message in hh:mm:ss

           <ticks>   time of message in machine ticks since boot

           <level>   tracing priority level

           <flags>   E : message is also in the error log
                     F : indicates a fatal error
                     N : mail was sent to the system administrator

           <mid>     module ID number of source

           <sid>     sub-ID number of source

           <text>    formatted text of the trace message

      Once initiated, strace will continue to execute until terminated by the
      user.

EXAMPLES
      Output all trace messages from the module or driver whose module ID is
      41:

            strace  41 all all

      Output those trace messages from driver/module ID 41 with sub-IDs 0, 1,
      or 2:




10/89                                                                    Page 1

strace(1M)        UNIX System V(Networking Support Utilities)        strace(1M)


            strace  41 0 1  41 1 1  41 2 0

      Messages from sub-IDs 0 and 1 must have a tracing level less than or
      equal to 1.  Those from sub-ID 2 must have a tracing level of 0.

SEE ALSO
      log(7)
      Programmer's Guide: STREAMS

NOTES
      Due to performance considerations, only one strace process is permitted
      to open the STREAMS log driver at a time.  The log driver has a list of
      the triplets specified in the command invocation, and compares each
      potential trace message against this list to decide if it should be
      formatted and sent up to the strace process.  Hence, long lists of
      triplets will have a greater impact on overall STREAMS performance.
      Running strace will have the most impact on the timing of the modules and
      drivers generating the trace messages that are sent to the strace
      process.  If trace messages are generated faster than the strace process
      can handle them, then some of the messages will be lost.  This last case
      can be determined by examining the sequence numbers on the trace messages
      output.
































Page 2                                                                    10/89